Update BatchObservableCollection to ObservableCollection
Fix settings corruption
Acquire mutex for settings
Update WP toolkit, make sure everything builds again
Update ads
Do not show back tile... ever
Remove random loader
Faster loading times
Update icons
Bump version to 2.9.1
Merge branch 'master' into adfree

Conflicts:
	OnThisDayApp/MainPage.xaml
	OnThisDayApp/Properties/WMAppManifest.xml